Audi's former CEO, meanwhile, remains in jail.
And what's this we hear about an unnamed Chinese gang?
Says 'circle of five' automakers held meetings to limit clean-air controls.
Rules would also set an interim goal of a 20 percent reduction by 2025.
They argue VW should have informed shareholders.
Buybacks of 500,000 cars will continue through 2019.
The move means Audi will likely be beat to punch by rival Mercedes.
Scandal pits Porsche-Piech families against labor, regional interests
Authorities hold Stadler in "investigative detention," afraid he'll try to suppress or change evidence otherwise.
This on top of the $4.3 billion fine in the U.S.
Prosecutors search homes of Rupert Stadler and one other board member
Report: Daimler's whole fleet of latest Euro 6 vehicles may have them.
750,000 Mercedes vehicles could be affected.
Fiat Chrysler Chief Executive Officer Sergio Marchionne reprimanded the company's top U.S. spokesman for issuing press releases about Fiat's vehicle emissions practices days after Volkswagen's disclosure in September 2015 that the German automaker had used illegal software to evade emissions tests, documents released Monday show.
Audi has discovered emissions-related problems with a further 60,000 cars, it said on Tuesday, dealing a fresh setback to parent Volkswagen more than 2½ years after it first admitted to cheating U.S. diesel exhaust tests.